1. Field of the Invention
This invention relates to stabilized vehicles and, more particularly, to air bag energy absorbing systems for trucks, tractors and trailers equipped with spring or walking beam suspensions.
2. Description of the Prior Art
Air bag energy absorbing systems for trucks, tractors and trailers equipped with spring or walking beam suspensions effectively reduce road shocks transmitted through the tires, axles and suspension into the vehicle body; smooth out uneven road conditions; significantly reduce axle hop, bogie chatter and cargo damage; and provide air ride performance from the spring suspension. Cameron U.S. Pat. No. 4,033,607, the disclosure of which is hereby incorporated by reference, discloses such an air bag energy absorbing system. Air bag energy absorption systems cost less and are more reliable than the air suspension systems disclosed in the following U.S. Pat. Nos.: 2,862,725; 3,145,032; 3,214,188; 3,966,223; 4,033,607; 4,206,934; 4,453,736; 4,553,773; 4,603,843; 4,619,467; 4,871,189; 4,903,984; 4,998,749 and 5,052,713.
The Load-Air.TM. system, manufactured by Load-Air, Inc. of 730 Superior Street, Carnegie, Pa. 15106, assignee of the Cameron patent, is made in accordance with the teachings of the Cameron patent. The Load-Air.TM. system includes two air bags supported from a seat attached to an axle of a vehicle, and a cross member attached to a vehicle frame. The suspension system carries the load and the Load-Air.TM. system absorbs the impact energy and provides a dampening effect on any axle upward thrust before it is transmitted to the vehicle.
Air is supplied at a constant pressure from the vehicle's air system to the air bags. The pressure of the air supplied to the bags is manually controlled by the vehicle operator. Generally, a low pressure is used for a vehicle in an unloaded condition and a high pressure is used for a vehicle in a loaded condition. However, it is not uncommon for a vehicle operator to fail to manually adjust the air bag pressure to correspond with a respective load condition or change in load condition, i.e. the air pressure is maintained at a level appropriate to a loaded condition even if the vehicle is in an unloaded condition. This can result in an uncomfortable ride for the vehicle operator and accelerated wear of a number of the vehicle components.
Therefore, it is an object of the present invention to provide an air bag energy absorbing system for a vehicle that automatically adjusts the air bag pressure as a function of the loaded condition of the vehicle.